Posted
by
kdawsonon Monday July 20, 2009 @11:23PM
from the like-a-perp-walk-only-without-the-cameras dept.

An anonymous reader recommends an Ars Technica account of a breakthrough in efforts toward quantum computing. German scientists have managed to get cesium atoms in a state called a "quantum walk": basically a superposition of all the possible states of a particle. "Quantum walks were first proposed by physicist Richard Feynman and are, in terms of probability, the opposite of a random walk. A random walk might be modeled by a person flipping a coin, and for each flip he steps left for heads and right for tails. In this case, his most probable location is the center, with the probability distribution tapering off in either direction. A quantum walk involves the use of internal states and superpositions, and results in the hypothetical person 'exploring' every possible position simultaneously." In the abstract of the paper from Science (subscription needed for full-text access), the researchers say: "Our system allows the observation of the quantum-to-classical transition and paves the way for applications, such as quantum cellular automata."

A working AND cost effective quantum computer capable of decrypting your pr0n is still a ways off.

If someone wants to spend that kind of money and resources to get you, then it doesn't matter what kind of decryption they have. If they can't ruin you by decrypting your secrets then they can just make something up. Fake compromising information is going to be the easier way to go for long enough that you shouldn't have to worry about it. I mean a planted local news story or thorough facebook+myspace+bl

It's probably less about people "getting you"(I suspect that, today, relatively few people are actually being protected from a hostile superior power by the strength of their crypto) and more with things like the breakdown of electronic commerce security, the spoofability of cryptographic signatures(Goodbye SSL) and new difficulties in secure authentication(SSH would be about as useful as telnet).

If a superior power simply wishes to ruin you that is, as you say, typically easy without any codebreaking. P

That, and the degree of effort required and risk is enough to make it worth their while. It's kind of like locking your car. If someone were to create a device that allowed someone to pass effortlessly through car windshields that doesn't automatically mean the device would be all that practically useful to a car thief. If it cost millions of dollars and required liquid nitrogen or helium cooling, then you're not going to see a rash of car thefts using said device, despite it appearance as a perfect tool

Encryption is nothing like a car lock. The cheap thieves aren't the ones we have to worry about with regard to encryption. Governments in fact are quite willing to spend many billions of dollars for a device which can crack citizens' encryption in order to help them control those citizens more effectively. Combine that with the internet -- a vast system of networks through which large amounts of data are piped and which, unfortunately, happens to contain large several bottlenecks at which governments can st

One important consideration you omit is that the superior power can't destroy everyone because their power depends on most people either supporting them or being rather apathetic about them. So the super power desires the means to acquire enough information about everyone to decide whom to eliminate. Now that information is (effectively) not encrypted? Their job just got easier.

If someone wants to spend that kind of money and resources to get you, then it doesn't matter what kind of decryption they have. If they can't ruin you by decrypting your secrets then they can just make something up.

Once they build, then harness this computer, we still have to wait 10 years for them to figure out how to program it without reading data, after all, once you observe the data, it will be changed. It's kinda like Safely Remove in Windows XP.

By using Plug and Play technology as it was intended, you have corrupted all your data. They invented a technology, and couldn't implement it, so it's useless, and some day they will figure it out.

Well, if you have used encryption for several years now, you probably made a move from 128bit over 512bit to 2064bit key size. For some encryption methods quantum computing will just be another step, but a really big one.For others, quantum computing may "solve the decryption" directly by the different approach (superposition, probabilistic calculations).

First of all, only public key encryption algorithms based on factoring would be broken. Others would still be strong (until a quantum algorithm was written to break them).

More importantly, properly applied one-time-pad encryption would still be unbreakable. I wouldn't be surprised if certain military/intelligence organisations were already using one-time-pad's that were distributed before missions (on DVD or HDD).

It is also worth noting that public-key encryption is already breakable at typical bit-strength

Quantum key distribution is already available commercially, see for example:

http://www.idquantique.com/

Quantum computers do still have a very long way to go before they are useful for anything else than factorizing very small numbers. The last record I heard of was 15, which was already quite a while ago, but I find it unlikely that they have managed to do any significant improvements since then.

We don't know that a quantum computer will be able to break every encryption scheme we have. We have the famous open problem of whether P=NP. (I'd bet against.) For those who don't know, P is the set of all problems solvable in polynomial (that is, relatively quick) time, and NP is the set of all the problems solvable in polynomial time if only it was practical to try every possible solution in parallel, or there was some fast (polynomial time or

Try to google for Post-Quantum Cryptography, only Public Key Cryptography is in danger, traditional symmetric algorithms are not affected much by quantum computers. There are public key algorithms which might be resistant to quantum computing, but only time will tell for sure:)

Cesium is an interesting element in that it is perfectly reliable. While some elements will differ in atomic weight due to random changes in their electron sphere radii and the number of neutrons in the nucleus, Cesium has a perfect vibration rate independent of external stimuli. It is so regular and reliable, in fact, that we base our entire measurement of time on clocks composed purely of Cesium.

If, as is demonstrated here, Cesium can be used to explore multiple quantum states in a regular and reliable fashion, the possibility to build quantum computers and automata based on Cesium goes way up. Not only would these "computers" function better than our current computers, they would always be 100% perfect (unless Intel manufactures them, lol) and not prone to error or breakage.

There is different isotopes of Cesium too, it is just that they have chosen one specific isotope for the measurements. In that regard Cesium isn't unique at all. I don't know what you mean with the "random changes in their electron sphere radii", but I don't see how Cesium would be different from other alkali elements in that regard.The last part of your comment is just false. There are problems that quantum computers would be able to solve that you can't solve with any practical classical computer, but the

You don't even know how to troll properly. I'm Scandinavian, and the only reason I chose to spell Cesium in this way was because that was how it was spelled in the post. When in Rome...
You have now not only proved your illiteracy, but also your stupidity by your unfounded conclusions, you inbred gnome.

I do hope that no one is suggesting that the clocks are made purely by cesium. What they do is that they measure the hyperfine splitting frequency of cesium and calibrate their clocks to make sure that the frequency they measure is exactly the value they should get according to the definition of a second in terms of the cesium hyperfine splitting frequency.

As far as I know it, we have three main instruction sets. Integer, Floating Point, and Vector (SSE, MMX..etc). Would it more likely be that we would end up with the forth set being Quantum? Or, would it be possible to have an entire CPU quantum based?

To your first question: Yes. There would be a new instruction set called "Eigen". It would contain all possible values simultaneously. The interesting thing about such a value is that it could be used to determine the correct value of any problem simply by casting it to the appropriate data type. Since the other instruction sets can only contain a single value at any time, the correct value (for our universe) is automatically saved in the other data type.

Nope, and this is a good straight line for my futile quest to explain something about quantum weirdness, because it is precisely the difference between "maybe" and "superposition" that makes life interesting for a quantum mechanic.

"Maybe" is a classical concept. If we see a cat get into a box, and then there is a sudden yowling and howling from the box, and you ask me, "Is the cat ok?" and I reply, "Maybe" we are talking about a classical situation, in whi

Nope. This is exactly the point I was trying to make: extremely short wavelengths explain why we don't observe interference phenomena. But they don't explain why we don't observe the cat as being in a superposition of ALIVE and DEAD.

That is, they don't explain why the world of experience differs from the quantum world, and this is the central question.

GIVEN that the only way we can detect the quantum world is via interference phenomena, then the really short wavelength of macroscopic objects explains why

Your answer will never be a superposition. You prepare the initial steps into superpositions and then use superpositions in the calculations, but you will get a definite answer in the end. Of course you can run your computer many times and if your programming is such then you can get different answer for each run even if the inputs were the same.

"The interesting thing about such a value is that it could be used to determine the correct value of any problem simply by casting it to the appropriate data type."

This is incorrect. Determining the superposition's state won't give you the correct answer. It will give you a random answer from all of its possible states -- weighted by the chance of that being the right answer. This makes quantum computing much trickier.

It might be inaccurate to call any quantum computer an "entire CPU" even when it is the processor of interest in a given system. While they are currently more of an experiment that is being observed and manipulated with the aid of traditional computing devices and lasers, even when they are more refined they are more likely to fill the roll of a sort of co-processor. This is because although they theoretically do certain tasks far better than a traditional processor (or, in the case of integer factorizati

As far as I know it, we have three main instruction sets. Integer, Floating Point, and Vector (SSE, MMX..etc). Would it more likely be that we would end up with the forth set being Quantum? Or, would it be possible to have an entire CPU quantum based?

Quantum computation is unlikely to replace classical computation. There are certain problems at which quantum computation excels (problems that involve period-finding in some way, shape, or form) and many problems that it doesn't excel at (anything else).

A quantum encryption co-processor is most likely the first way in which quantum computation will reach the classical computing world, and for physical reasons (you need an actual quantum communication channel to attach to) I wouldn't expect it on your

As far as I know it, we have three main instruction sets. Integer, Floating Point, and Vector (SSE, MMX..etc). Would it more likely be that we would end up with the forth set being Quantum? Or, would it be possible to have an entire CPU quantum based?

Sure it would. Modern processors do things with several bits at once (like 32 or 64 bits integers, floats that you mention). Quantum computer calculates with several quantum-bits (so-called q-bits) at once, using their entanglement together with quantum evolution and a measurement on the evolved q-bits. This has nothing to do with some word Eigen that other posts are mentioning, because we can simulate quantum computers classically, so Eigen is not necessarily operation that only quantum computer does--w

Theoretically speaking, if we could get, say, an entire ship and all of its inhabitants to do this "quantum walk"...

Ah, but you can't. Quantum mechanics applies only to quantum particles, not big honking spaceships. Of course nobody has integrated quantum mechanics with classical mechanics yet, so you never know;)

The thing is, quantum mechanics is just a mathematical system that seems to work pretty well. As in, it predicts what really tiny things will do extremely well. When a quantum particle takes on different states at a time, that is a mathematical concept that, when applied, produces a result that agrees w

Actually Quantum Mechanics applies to individual atoms regardless of size. Classical mechanics corresponds to the mathematical limits when the number of particles becomes large, i.e. you take the mathematical constructs of quantum mechanics and extrapolate to the number of particles being infinity and you come up with the mathematical construct for Classical Mechanics.

So Anpheus is correct. How do I know this? Well, I have a Ph.D. in Physical Chemistry.

From what I've read on the issue, such as Feynman's books and other novels targeted toward those of us who do not have a complete grasp of quantum mechanics, you are wrong.

Caveat emptor, this is merely what I've read:

Classical mechanics as explained by Feynman were the result of the sum of all possible histories, among other interpretations. Regardless of one's interpretation, Feynman and others found that as you crunch the math for larger and larger quantities of particles, the results closer and closer approximate what we think of as classical physics. As a result, classical physics is an approximation of quantum mechanics, which is a theory of how the universe really works.

If you download the 2009 intro to General Principles of Chemistry from the mit OpenCourseWare offerings you'll get some pretty good stuff on the relationship of Quantum Mechanics and Classical Physics. IIRC the wave descriptions of big league fast balls are used (lectures 4 & 5). I'll leave it there as any attempt by me to go into the particulars will go high and outside.

It is really a beautiful experiment. I have never seen such a demonstration of how deterministic the propagation of the wavefunction is. By simply running the experiment backwards they manage to get the atom to go back to it's initial position in the walk.

lt's not particularly quantum, is it? I'm afraid that the Ministry of Quantum Walks is no longer getting the kind of support it needs. You see there's Defence, Social Security, Health, Housing, Education, Quantum Walks... they're all supposed to get the same. But last year, the Government spent less on the Ministry of Quantum Walks than it did on National Defence!

When talking about quantum computing, don't forget that someone has to write the programs. If you thing programming in a SIMD (Single Instruction Multiple Data) is difficult, try SIID (Single Instruction, Infinite Data).

Also remember that there are a few REALLY hard problems to solve before we can have a quantum computer compute anything. For example, to factor a key, you have to have two 'registers' and somehow get them to be the superposition of all primes less than the key value. That is, all non-primes

D-Wave Systems is quite suspect and doesn't have much respect in the scientific community. On the other hand, Quantum Computing (QC) does rest on sound scientific principles, and in the quest for it we learn a lot. The gain if we succeed would be enormous. It is easy to get the impression that quantum computing only can be used for factorizing numbers, but the big gain would rather be in other fields of science, such as medicine and biology where we would use QC to simulate e.g. proteins.The link you provid

Not it doesn't. It only questions the Copenhagen interpretation of quantum physics, especially the concept of superposition of quantum states. An interpretation is not a theory. It is just a guess. In this case, it is a very lame guess and silly on the face of it.

Superposition of states is fundamental to quantum physics and not a part of the Copenhagen interpretation. The principle of superposition has been tested over and over again and is as far from a guess as you can come. Especially since it is counter-intuitive it has been scrutinized and tested more than most fundamental principles in science.

This is BS and you know it. Superposition is certainly part of the Copenhagen interpretation [wikipedia.org]. The hard irrefutable truth is that nobody has ever observed superposed states. The only thing that is tested is the probabilistic nature of quantum interactions. The entire concept of a wave function collapse is just silly guess work. One could just as easily say that the property has a given state but the state can instantly change when the particle interacts with another (during observation) in order to obey cons

Superposition is not a part of only the Copenhagen interpretation. You obviously didn't read the Wikipedia article you link to. It doesn't even contain the word superposition.

No, no one has ever observed superposed states, since the wavefunction collapses as soon as anyone try to observe it. It is not silly guesswork. The brightest minds in modern time have failed to come up with any other explanation. Einstein was only one of them. You can not say "the property has a

What are you, a wise guy? Bell's inequality is about entangled particles and nonlocality. That has nothing to do with superposition of states. The Copenhagen interpretation has to do with the Schrodinger wave function, which is about superposition. You don't even understand the very theory you're arguing about.

The only reason that quantum mechanics is counterintuitive and hard is that physicists are clueless as to what is really going on. This should be a clue that current interpretations are wrong and shou

Bell's inequality says, loosely speaking, that if you have locality then you must have superpositions. Most physicists thinks we have locality, otherwise information could be transmitted faster than light. If information can be transmitted faster than light, we get problems with causality and then we are in a real mess. Then you could really start to talk about counterintuitive.

The Schroedinger equation is central to quantum physics. It describes how a state evolves with time. Again, it is not something tha

Sorry, nonlocality does not imply fater than light communication. Those who worry about faster than light travel simply do not understand the science of nonlocality. Nonlocality means nonspatiality, i.e., distance is an illusion. There is no transmission of information between two entangled particles. They are facets of the same coin. Nonspatiality should be a wake-up call to physicists, IMO. The paradigm shifting implications threaten to revolutionize physics. Thomas Kuhn comes to mind.

Quantum physics is very logical. It is just counter intuitive. That you can't understand it, doesn't mean it is illogical. Kuhn's paradigm shift did already happen. It happened with the advent of Quantum Physics. It's just that you haven't caught up yet.

I'm sorry, but you are obviously just a tiresome crackpot. You don't understand quantum physics. You don't understand superpositions or entanglement. You give up relativity and the notion of space to save what you call logic. Your post doesn't contain any su